[PATCH 4.9 41/58] kvm: vmx: Fix entry number check for add_atomic_switch_msr()

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xiaoyao Li <xiaoyao.li@xxxxxxxxxxxxxxx>

commit 98ae70cc476e833332a2c6bb72f941a25f0de226 upstream.

Commit ca83b4a7f2d068da79a0 ("x86/KVM/VMX: Add find_msr() helper function")
introduces the helper function find_msr(), which returns -ENOENT when
not find the msr in vmx->msr_autoload.guest/host. Correct checking contion
of no more available entry in vmx->msr_autoload.

Fixes: ca83b4a7f2d0 ("x86/KVM/VMX: Add find_msr() helper function")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/kvm/vmx.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2178,7 +2178,8 @@ static void add_atomic_switch_msr(struct
 	if (!entry_only)
 		j = find_msr(&m->host, msr);
 
-	if (i == NR_AUTOLOAD_MSRS || j == NR_AUTOLOAD_MSRS) {
+	if ((i < 0 && m->guest.nr == NR_AUTOLOAD_MSRS) ||
+		(j < 0 &&  m->host.nr == NR_AUTOLOAD_MSRS)) {
 		printk_once(KERN_WARNING "Not enough msr switch entries. "
 				"Can't add msr %x\n", msr);
 		return;